From the interview:
Q. What made you decide to make the figures larger than 28mm?
There were a number of factors.
From the start, we wanted our figures to appeal not only to tabletop gamers but also to Doctor Who fans and collectors. This led us down the route of producing photo-realistic models as Whovians outside of the gaming world wouldn’t appreciate the usual big head, ham fists and short legs on traditional wargames figures. When you’re paying a licence, you want to make sure you replicate the look of the subject matter rather than caricature and exaggerate them.